Flat Band and η-Pairing States in a One-Dimensional MoiréHubbard Model  

作　　者：王冉 宋智 R.Wang;Z.Song(College of Physics and Materials Science,Tianjin Normal University,Tianjin 300387,China;School of Physics,Nankai University,Tianjin 300071,China)

机构地区：[1]College of Physics and Materials Science,Tianjin Normal University,Tianjin 300387,China [2]School of Physics,Nankai University,Tianjin 300071,China

出　　处：《Chinese Physics Letters》2024年第4期69-76,共8页中国物理快报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.12305026 and 12374461)。

摘　　要：A Moirésystem is formed when two periodic structures have a slightly mismatched period,resulting in unusual strongly correlated states in the presence of particle-particle interactions.The periodic structures can arise from the intrinsic crystalline order and periodic external field.We investigate a one-dimensional Hubbard model with periodic on-site potential of period n_(0),which is commensurate to the lattice constant.For large n_(0),the exact solution demonstrates that there is a midgap flat band with zero energy in the absence of Hubbard interaction.Each Moiréunit cell contributes two zero energy levels to the flat band.In the presence of Hubbard interaction,the midgap physics is demonstrated to be well described by a uniform Hubbard chain in which the effective hopping and on-site interaction strength can be controlled by the amplitude and period of the external field.Numerical simulations are performed to demonstrate the correlated behaviors in the finite-sized Moiré Hubbard system,including the existence of an η-pairing state and bound pair oscillation.This finding provides a method to enhance the correlated effect by a spatially periodic external field.

关 键 词：OSCILLATION INTERACTION field 

分 类 号：O469[理学—凝聚态物理]